The invention relates to a packaging machine and in particular to a packaging machine for packing products in containers formed in a sheet material and sealed with a cover sheet. The invention also relates to a package produced by such a packaging machine and a method of producing such a package.
It is generally known to provide packaging machines forming containers in a sheet material, filling the containing and closing the containers by sealing a cover sheet to an edge of the containers in an evacuation and sealing station. It is further known from the U.S. Pat. No. 3,792,181 to provide formed containers of that kind which can be reclosed after opening the same by removing the cover sheet from the sealed edge. To this end the upper portion of the container adjacent to the container edge comprises a bulbous depression. The cover sheet has a projecting protuberance at the corresponding location. The protuberance is pressed into the depression for reclosing the container. The connection is locked by friction between the cover and the container. A disadvantage of such a package is the troublesome forming process because of the undercut-type depression. Such a depression must be formed in the container already in the deep drawing station and in the cover sheet in the sealing station while keeping to close tolerances. Additionally the particular deformation of the container must be designed and formed for each container mold individually, because it forms part of the actual container mold. Whenever the size of the product is changed, the container and the apparatus for producing the depression must also be changed. It is further known from the aforementioned patent to design the edge surrounding the actual containers such that a nose of the container edge engages the cover sheet or two differing cuts in the container edge and in the cover sheet are brought into mutual engagement. However, these engagements only provide for a limited connection and complicated handling, resp.
The U.S. Pat. No. 3,311,229 discloses a package for tablets held between two sheets which are connected by means of a snap fastener formed by deformation of one or both sheets.